1. Technology Field
The present invention generally relates to semiconductor optical sources. In particular, the present invention relates to a laser device having a passivation layer that reduces parasitic capacitance while also minimizing mechanical stress components of the laser in order to preserve the integrity and structure of the device, especially with regard to lasers configured for high data rate operation.
2. The Related Technology
Semiconductor lasers are currently used in a variety of technologies and applications, including communications networks. Generally, lasers produce a stream of coherent, monochromatic light by stimulating photon emission from a solid state material. Fabry-Perot (“FP”) and distributed feedback (“DFB”) lasers are exemplary laser designs commonly used in optical transmitters, which are responsible for modulating electrical signals into optical signals for transmission via a communications network, for instance.
Semiconductor optical sources, such as the lasers described above, generally include a passivation layer that covers selected portions of the device so as to electrically isolate it from adjacent devices, and to environmentally protect it from contamination, humidity, etc. Importantly, the passivation layer also reduces parasitic capacitance in the laser, enabling it operate as intended.
With the advent of ever-higher data rates in communications networks, lasers are being developed to operate at 2.5, 10, and higher Gigabit/second data rates. As laser data rate operability rises, so too does the required passivation layers thickness. Increase in passivation layer thickness is necessary to offset the increased influence of parasitic capacitance that is present during high-speed laser operation. Unfortunately, with an increase in passivation layer thickness comes increased mechanical stress that is introduced into the layer. Indeed, these mechanical stresses can be such that cracking or rupture of the passivation layer may occur, which can compromise the integrity of the laser, rendering it unusable.
In light of the above, a need exists in the art for a laser device having a passivation layer that can adequately protect the device from parasitic capacitance while not suffering from the above-described problems.